Safety-fuse.



N0. 660,34] Patented Oct. 23, I900.

J. SACHS.

SAFETY FUSE.

(Application filed Nov. 24, 1899.)

(No Model.)

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rttT'en STATES PATENT Orrice.

JOSEPIISACHS, OF HARTFORD, CONNECTICUT.

SAFETY-FUSE.

PECIFICATION forming part of Letters Patent No. 660,341, dated October 23, 1900.

Application filed November 24, 1899. b'erial No. 738,119. (No model.)

To all whom it may concern.-

Be it known that l, JOSEPH SACHS, a citizen of the United States, residing at Hartford, in the county of Hartford and State of Connecticut, have invented an Improvement in Safety- Fuses,of which the following is a specification.

Safety-fuses have usually been heretofore inclosed in a tubular ease and surrounded with a filling of non-conducting material. These fuses have consisted of a wire which when fused by an excess current was maintained in place in a melted state by the surrounding filling material and the fused metal still served to carry the current for a period until the same gradually became dispersed in the interstices of the filling and the circuit broken. have been of lead orlead-tin alloy, and since this metal has a low conductivity a very large section of metal was used for the fuse-wires to carry the current, and this large section when fused was difficult to disperse in the filling material. This hanging of the fusewire in a melted state made such fuses inaccurate as to their carrying capacity. I have discovered that the non-arcing qualities or action of a fuse depends upon the disposition, character, and amount of the metal and that for this purpose a fuse-strip having a relatively small quantity of metal will give the best results. I have also discovered that the best results are obtained from the use of a metal which when melted or fused rapidly oxidizes even if the melting-point of the metal is not comparatively low.

My invention relates to a sa fety-fuse of metal made thin and fine and disposed through an appreciable area of the tube-section, and the same preferably consists of a flat thin strip held between terminals having a better conductivity than the fuse itself, said strip be ing preferably of a rapidly-oxidizing metal. A fuse of this character placed in a tubular case and surrounded with a non-conducting filling and fused by an excess current will not only rapidly oxidize, but become quickly dispersed in the interstices of the filling material. Where the surrounding material comloines with the fused wire, the combination is more readily accomplished because of the greater surface of material exposed in the fuse-wire and in contact with the surround- The fuse-wires used in such fuses ing material. I have found that zinc or an alloy of zinc is best suited to my purpose and that the thinner and finer the metal and the greater the spread thereof the better. here the non conducting filling material is of a character to combine with the fuse-strip when melted, the thin strip of increased meltingpoint is an advantage. The thin fine strip of metal is distributed through a larger section of the inclosed filling and thus on disruption more readily. dispersed through the interstices of the filling than if the strip were of compact sectional area.

In the drawings, Figure 1 is a longitudinal section and partial elevation representing my improvement. Fig. 2 is a cross-section of the same at :0 a; of Fig. 1, and Figs. 3 and 4 represent modified forms of fuse-strips.

The tubular inclosing case a is preferably made with metal ends a connected thereto, and the case is provided with a non-conducting filling b.

In Figs. 1 and 2, 0 represents the fusible strip, and (7, terminals connected thereto of better conductivity than the fusible strip 0, the terminals being within the case, with the ends projecting and connected to the external terminals or connections 6. The strip 0 is of very thin fiat metal, occupying considerable area across the case, and in the same there is a relatively small quantity of metal, and the metal is preferably one that rapidly oxidizes. This I prefer to be a strip of zinc or an alloy of zinc, the terminals d, connected therewith, being of greatersize and better conductivity and of course being so far distant from one another within the case that when the strip 0 is fused and disperses in the interstices of the filling said terminals are too far apart for the passage of any current or spark or for the existence of any areing condition. If this thin strip is melted by an excess current instead of remaining in place in the filling, as would a wire of com pact section, it is dispersed quickly in the interstices of the filling upon either side of the thin strip, so that the circuit is broken immediately. I am enabled to accomplish the same result by using the form of strip shown in Fig. 3, where the terminals 1 are integral and of the same material, but wider than the central strip a, and in which of course the action of the excess current would be to destroy the narrow central strip 0 before melting the ends (1'.

In the form shown in Fig. 4 the cross-sectional area of the thin strip is extended and bent into the U'form c, the action of which will be the same as that described in connection with the other parts. In the drawings this strip is illustrated in a cross-section of magnified form for clearness. This strip may be exceedingly thin.

As hereinbefore stated, I not only prefer to make the fuse-strip of thin metal of an extended area, but to make the same of such metal, as zinc or an alloy of zinc, that rapidly oxidizes when fused, and I may use in connection with these fuse-strips a filling material of a character to combine with the fuse-strip when melted; hut I do not limit myself to this form of filling.

I claim as my invention- 1. A safety-fuse comprising a case and a filling of non-conducting material and a fusestrip therein of thin flat metal of extended area, substantially as and for the purposes set forth.

2. The combination in a safety-fuse with a tubular case and a non-conducting filling ma terial, of end terminals within the case of relatively ample conductivity, and a fuse-strip of thin fiat metal of extended area connected to and between the said terminals, substantially as and for the purposes set forth.

The combination in a safetysfuse with a tubular case and a non-conducting filling material, of end terminals within the case of relatively large area and ample conductivity, and

a fuse-stri p of thin flat metal of extended area connected to and extending between the said terminals, metal ends to the case and through which the terminals pass, and external terminals or connections outside of the said ends and connected to the inner terminals, substantially as and for the purposes set forth.

4:. The combination in a safety-fuse with a tubular case and a filling of non-conducting material, of a fuse and terminals within and extending through the case, the fuse being of thin flat metal of extended area with the ends thereof wider than the central portion, substantially as and forthe purposes set forth.

5. A safety-fuse comprising a case and a filling ot' n(in-conducting material and a single flat fusestrip therein, of thin metal of extended area and maximum contact with the filling material and terminals at the ends of the fuse-strip and case, substantially as set forth.

6. The combination in a safety-fuse with a tubular case and ends for closing the same and a non-conducting filling within the same, of a thin fine fuse in a flat plane consisting of a rapidly-oxidizing metal and terminals of relatively better conductivity connected to the respective ends of the flat fuse at the ends of the case, substantially as and for the purposes set forth.

Signed by me this 18th day of November, 1899.

JOSEPH SACHS.

Witnesses:

S. T. HAVILAND, HAROLD SEnnnLL. 

